Air start valve

ABSTRACT

A fluid-actuated air valve adapted to apply operating air in two pressure stages to an air motor by a pair of normally closed operating heads mounted on a common stem and automatically opening in sequence in response to fluid pressure applied to a common actuated head.

United States Patent Inventor Virgil L. From: [56] I References CitedSalem, UNITED STATES PATENTS g 3535 1969 2,888,953 6/1959 Gratzmuller137/630. 15

1 Patented Jan. 4 1972 3,439,711 4/1969 Sherwood et a1. 137/630. 15Assignee Graham-White Sales Corporation FOREIGN PATENTS Salem, VI.287,719 3/1928 Great Britain 137/630. 1 5 496,294 8/1954 ltaly 137/630.1 5 AIR START VALVE Primary Examiner--Robert G. Nilsorl 6 Claims, 3Drawing Figs Attorney-Wilmer Mechlin US. Cl 137/630.15 Int. Cl Fl6k l/54ABSTRACT: A fluid-actuated air valve adapted to apply Field of Search137/630. 15, Operating air in two pressure stages to an air motor by apair of 630.19 normally closed operating heads mounted on a common stemand automatically opening in sequence in response to fluid pressureapplied to a common actuated head.

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Inventor: Virgil L. Frantz his Attorney AIR START VALVE BACKGROUND OFTHE INVENTION An air motor, such as used for starting a diesel engine ofa diesel locomotive, ordinarily has on its rotor, vanes that collapsewhen the motor is stopped and must be projected before the motor candevelop sufficient torque to crank and start the engine. Both theinitial projection of the vanes and the subsequent tuming of the rotorat full torque are produced by operating air applied to the motor.However, if, as in the usual installation, the operating air is appliedthrough a pilot-controlled operating valve capable of deliveringoperating air only at full pressure and volume, breakage of the vanes orother damage to the air motor can readily result. Recognizing this, ithas heretofore been proposed to deliver air to the motor throughseparate, individually valved lines, one a low pressure pilot line ofthe initial delivery and the other a main supply line equipped with adelayed action valve responsive in opening to pressure from the pilotline. The present invention affords a more practical solution for thesame problem.

SUMMARY OF THE INVENTION The primary object of the present invention isto provide an improved fluid-actuated valve for the operating air supplyline of an air motor, which upon actuation will automatically supplythrough the line a first stage of low pressure starting air and secondstage of operating air at full pressure and volume.

Another object of the invention is to provide an improved operatingvalve of the character described, wherein the two pressure stages areproduced by a single valve assembly having low and high-pressureoperating heads mounted on a common stem and automatically unseated insequence by actuating pressure applied to a common actuating head.

Other objects and advantages of the invention will appear hereinafter inthe detailed description, be particularly pointed out in the appendedclaims and be illustrated in the accompanying drawings, in which:

FIGURE DESCRIPTION FIG. 1 is an end elevational view of a preferredembodiment of the improved operating valve of the present invention;

FIG. 2 is a vertical sectional view on an enlarged scale taken alongline 2-2 of FIG. 1; and

FIG. 3 is a somewhat schematic plan view combining the operating valveof FIG. 1 with an air start motor and a control valve.

DETAILED DESCRIPTION Referring now in detail to the drawings in whichlike reference characters designate like parts, the improved twostageoperating valve of the first invention, designated as I, is designed forconnection in an operating air supply line 2 of an air start motor 3,such as used for starting a diesel engine (not shown) of a diesellocomotive (also not shown).

Of the poppet type, the improved operating valve 1 preferably is astraight-way valve comprised of a body or casing 4 having at oppositeends for connection in the operating air supply line 2 inlet and outletports 5 and 6 opening inwardly onto inlet and outlet passages orpassageways 7 and 8, respectively, the latter separated by a central webor 'wall 9 in and integral with the body and communicable or connectablethrough a centrally apertured main or primary valve seat 10 formed in ahorizontal intermediate portion of the web and opening or facingupwardly into the inlet passage. The main or primary valve seat 10 iscloseable from above by a disk-type main valve, valve element oroperating head 11 mounting or carrying an annular sealing gasket 12 forsealing engagement with the seat and normally held closed or inseat-closing position by a main coil return spring 13 yieldably actingdownwardly against the valves upper face 14 and conveniently received orseated in and reacting upwardly against a spring cap 15 threaded intothe top of the body 4.

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Concentric with but smaller than the main valve seat 10 and formed inthe upper face 14 of the main valve 11, is a secondary or auxiliaryvalve seat 16. Also facing or opening inwardly into the inlet passage 7,the secondary seat 16 is closeable by a disk-type secondary or auxiliaryvalve, valve element or operating head 17 carrying or mounting anannular sealing gasket 18 sealingly engageable with the seat and thisvalve is yieldably urged into and normally held in seated orseat-closing position by a secondary or auxiliary coil return spring 10within or inside and concentric with but weaker than the main spring 13.The secondary spring 19 is also received or seated in the spring cap 15and acts therebetween and an upper or outwardly facing face or surface20 on the secondary valve 17 Communication or connection of the inletand outlet passages 7 and 8 through the secondary seat 16 is restrictedrelative to that through the main seat 10, this restricted or meteredcommunication suitably being provided by an annular axial recess 21 inthe main valve 11 which opens upwardly through the secondary seat ontothe inlet passage and at its bottom within the main valve is in openconnection or communication with the outlet passage 8 through anobliquely disposed, restricted passage or orifice 22 extendingtherebetween through the intervening portion of the main valve.

The main and secondary valves 11 and 17 are both mounted on the same ora common valve stem or spindle 23 concentric or coaxial therewith andwith the main seat 10, the main valve slidably for limited axialsliding, shifting or lost motion and the secondary valve threadedly forthreading or screwing downwardly on a reduced threaded intermediateportion 24 of the stem against an upwardly facing shoulder 25 at thebottom of that portion. Limited in upward movement on the stem 23relative to the secondary valve 17 by that valve, the main valve 11 islimited in downward movement relative thereto by an upwardly facingoutstanding annular shoulder, abutment or stop 26 integral or rigid withthe stem and normally spaced below the main valve.

Guidingly or slideably received at its upper end in a central socket 27in the spring cap 15, the common valve stem 23, below the lower shoulderor stop 26, is guidingly or slidingly received in and extends through aguide aperture or opening 28 through the bottom wall 29 of both theoutlet passage 8 and the body 4 into a pressure chamber 30. Concentricwith the stem 23 and extending downwardly below the bottom wall 29, thepressure chamber 30 is closed at the bottom by a cover or cap 31 boltedor otherwise releaseably attached to and in operation forming part ofthe body 4.

Contained or riding and reciprocable or shiftable vertically in thepressure chamber 30 and fixed, as by swedging, to the lower end of thevalve stem 23, is an actuating head 32 having an underface or bottomsurface 33 of greater cross-sectional area than the surfaces presentedby the main and secondary operating valves 11 and 17 to the inletpassage 7. O-rings or like suitable sealing gaskets 34 on the actuatinghead 32 and the stem 23, efi'ectively seal against leakage therepast inthe pressure chamber 30 and the guide aperture 28, respectively.

Designed for fluid actuation, the single valve assembly comprised of theoperating heads 11 and 17, actuating head 32 and common stem 23, is soactuated by fluid pressure introduced into the pressure chamber 30 belowthe actuating head, while eliminating any back pressure by venting thepressure chamber to atmosphere above the head. Supplied separately fromthe valve body 4 through an actuating air supply line 35 under controlof a manually or otherwise suitably actuated control or pilot valve 36,the actuating air, for convenience in installation, presumably isadmissible from either side into the valve body 4 through either of apair of inlet ports 37 in opposite sides of the body, one connected tothe actuating air line and the other plugged in a given installation.Internally, each of the inlet ports 37 is connected or open to apassageway 38 leading downwardly therefrom through the lower part of thebody 4 and the cover 31 to the pressure chamber 30 below the actuatinghead 32. In the fluid connection between the pressure chamber and theactuating air line 35, the actuating air is forced to pass through arestricted orifice 39, which, most conveniently, is formed in a fittingor coupling 40 releasably connecting the line 35 to the valve body 4 forready replacement by an interchangeable fitting having an orifice ofdifferent diameter or cross-sectional area.

In operating the valve 1 for starting the air start motor 3 to starttheassociated diesel engine (not shown), the control valve 36 is manuallyor otherwise opened to supply actuating air to the supply line 35. Asadmitted or supplied to that line, the actuating air will be at the fullpressure of the source, usually on the order of about 150 psi. However,the flow of the actuating air from the line 35 to the pressure chamber30 is intentionally choked, throttled or restricted by forcing it topass through the restricted orifice 39 so as to produce a progressive orgradual rather than an abrupt buildup of the pressure in the chamber tothat in the line.

With the delayed pressure buildup in the pressure chamber 30 and a lostmotion connection between the valve stem 23 and the main valve 11, as aresult of the normal spacing of the stop 26 below that valve, but nonebetween the stem and the secondary valve 17, and the secondary spring 19weaker than the primary spring 13, the secondary valve will be unseatedbefore the main valve. Once the secondary valve is unseated,

' operating air can pass through the supply line 2 to the air startmotor 3, but only to the extent permitted by the restricted 'passage 22connecting the secondary seat 16 to the outlet passage and port 8 and 6.By contrast, upon the subsequent un seating of the main valve 1 1 theinlet and outlet ports 5 and 6 are in full communication and fulloperating pressure, usually in the range from 150 to 220 p.s.i., will bedelivered to the air motor through the then open main seat 10. Thecombined action of the gradual pressure buildup in the pressure chamber30, the lost motion connection between the valve stem 23 and the mainvalve 11, the relative weakness of the secondary spring 19 and thechoking, throttling or restricting of the flow through the supply line 2by the restricted passage 22 when only the secondary valve 17 isunseated, on opening of the control valve 36, will automatically causeoperating air to be delivered to the air start motor 3 in two pressurestages. One, a first or low-pressure starting stage sufficient toinitiate or start operation of the motor, but insufiicient to damage it,and the other, a second or full pressure operating state, the latteroperating the air motor under full power until the associated deiselengine is started.

Required only to start or initiate operation of the air start motor 3,the first or low pressure stage can and preferably is very short orbrief, a duration of about V4 secs. having been found adequate toprotect the air motor from damage. In the preferred valve, a shortduration first pressure stage is produced by using as the secondaryspring 19, one opening or yielding under a pressure of about 5 l0 psi.and as the main spring 13 one opening or yielding under a pressure ofaround psi. The valve assembly acting as a differential piston inopening the valve 1, the presented area of the actuating head 32 must besufficient, relative to the combined presented areas of the main andsecondary valves 11 and 16, to overcome, when subjected to fullactuating air pressure, both the resistance of the springs 13 and 19 andthe opposing pressure of the operating air on the two valves.

From the above detailed description it will be apparent that there hasbeen provided an improved air start valve for automatically deliveringpressure in two stages to an air start mo-- tor. It should be understoodthat the described and disclosed embodiment is merely exemplary of theinvention and that all modifications are intended to be included that donot depart from the spirit of the invention and the appended claims.

Having now described my invention, I claim:

1. The combination with an air motor and a line for supplying operatingair thereto, of an operating valve in said line, said operating valvecomprising a body having inlet and outlet ports, main and auxiliaryvalve seats in said body between said ports for respectively full andrestricted communication therebetween, main and auxiliary operatingheads in said body for closing respectlvelysaid mam seat and saidauxiliary seat, a

then said main seat on said shifting of said actuating head, and vrestricted means for delaying the pressure buildup in said pressurechamber, said springs and restricted means cooperating for deten'niningthe interval between opening of said auxiliary and main seats.

2. The combination according to claim 1, including valve means forcontrolling the supply of actuating pressure to the pressure chamber,and wherein the restricted means is positioned therebetween.

3. The combination of claim 2, wherein the springs are coil springscoaxial with each other and the stem.

4. The combination of claim 3, wherein the seats are coaxial with eachother and the stem.

5 The combination of claim 4, wherein the auxiliary seat is fonned inthe main valve.

6. The combination of claim 2, wherein the restricted means is arestricted orifice in a fitting removably mounted in the body andreleasably connecting thereto a'n actuating air supply line from thecontrol valve.

1. The combination with an air motor and a line for supplying operatingair thereto, of an operating valve in said line, said operating valvecomprising a body having inlet and outlet ports, main and auxiliaryvalve seats in said body between said ports for respectively full andrestricted communication therebetween, main and auxiliary operatingheads in said body for closing respectively said main seat and saidauxiliary seat, a main spring and a weaker auxiliary spring actingrespectively on said main head and as the sole biasing spring force onsaid auxiliary head for normally holding said heads in seat closingposition, an actuating head mounted in a pressure chamber in said bodyfor shifting therein in response to air pressure supplied thereto, avalve stem fixed to said actuating and auxiliary operating heads andlost-motion mounting said main operating head for automatically openingfirst said auxiliary seat and then said main seat on said shifting ofsaid actuating head, and restricted means for delaying the pressurebuildup in said pressure chamber, said springs and restricted meanscooperating for determining the interval between opening of saidauxiliary and main seats.
 2. The combination according to claim 1,including valve means for controlling the supply of actuating pressureto the pressure chamber, and wherein the restricted means is positionedtherebetween.
 3. The combination of claim 2, wherein the springs arecoil springs coaxial with each other and the stem.
 4. The combination ofclaim 3, wherein the seats are coaxial with each other and the stem. 5.The combination of claim 4, wherein the auxiliary seat is formed in themain valve.
 6. The combination of claim 2, wherein the restricted meansis a restricted orifice in a fitting removably mounted in the body andreleasably connecting thereto an actuating air supply line from thecontrol valve.